Restaurant

The Restaurant is a building in the train station which generates a profit every 1h 30m (express server: every 45m). Once the profit is generated, you (or your associates, see below) have to collect it by clicking it, before it starts generating again.

By upgrading the restaurant you'll increase the generated amount, but the waiting time doesn't change.

Upgrading your hotel increases the restaurant profit by a certain percentage for each hotel level.

Upgrading the restaurant can give you lot of cash, but it takes time to pay off at the higher levels, because the upgrades will get quite expensive.

The benefits of having a high level restaurant or shopping center are best used if you're in an association where others will collect the money for you when you're not on.

The restaurant is best upgraded as early in the game as possible, so you can benefit from it for a long time.

If we assume you start to generate money when you reach level 32, you have spent 69 624 000, it pays back roughly in 26,8 days, assuming you have no hotel bonus, and collect money 10 times a day. You might also get worker and its cheaper to upgrade buildings in train station, so the value is rounded up HARDLY. I wanted to know it, so I did some math for you